Device for removing dust and rubbish

ABSTRACT

A device for removing dust and rubbish includes a casing provided with a suction opening, a rotating brush, a turbine operationally connected to the brush, a suction nozzle located between the brush and the turbine, and a suction pipe connected to a suction device; the brush and the turbine are rotatably supported, respectively, in a first and in a second housing; the device also includes at least a bypass duct and a first valve, the bypass duct being designed for bypassing the second housing and the turbine, the first valve being able to engage with the suction nozzle and with the bypass duct for closing the suction nozzle and opening the bypass duct. (FIG.  1 )

[0001] This application is based on European Patent Application No.00830053.5 filed on Jan. 28, 2000, the content of which is incorporatedhereinto by reference.

[0002] The present invention relates to a device for removing dust andrubbish from a surface, for example a fabric surface, such as amoquette, carpet and the like, or from a bare surface, such as a tiled,marble, wooden (parquet) and similar type of floor.

[0003] Conventional devices for removing dust and rubbish, provided witha turbo-brush head which may be replaced by a simple suction head, areknown. In most cases the former is used to clean fabric surfaces, whilethe latter is used to clean bare surfaces.

[0004] Generally, the turbo-brush head includes a rotating brushprovided with bristles and actuated by a turbine with radial vanes. Therotating brush and the turbine are rotatably supported in two housingsinside a casing. The casing has a suction opening, inside which therotating brush is placed, and a suction nozzle located between therotating brush and the turbine. A suction pipe connected to a suctiondevice communicates with the suction nozzle and the turbine housing.

[0005] When the suction device is in operation, an air flow passesthrough the suction opening, the nozzle and the suction pipe and strikesthe vanes of the turbine, causing the latter to rotate. The turbinetransmits the rotary movement to the brush via a toothed belt, and thebrush, rotating, with its bristles passes over the surface to be cleaned(fabric surface, which may be padded, tapestry, furnishing, moquette,carpet and the like), removing the dust and the rubbish which are suckedup by the air flow generated by the suction device.

[0006] The simple suction head, in turn, includes its own suctionopening which is placed in communication with the suction pipe connectedto the suction device.

[0007] JP-06098840 discloses a vacuum cleaner having a suction air flowwhich is turned into a jet flow after passing through a nozzle to rotatean impeller and then it is turned into an exhaust air flow. Rotation ofthe impeller of the turbine rotates a rotary brush through a timingbelt. A main nozzle and a bypass nozzle are positioned on a nozzlesupporting plate and the cross-sectional shape of the nozzle is madeinto a circular form or an elliptic form. A plate shutter is engageablewith the bypass nozzle to close it. The main nozzle is used for a heavyloading such as a carpet and the bypass nozzle is used for a relativelylight loading such as a tatami mat or a wooden flooring.

[0008] The circular or elliptic form of the nozzle has the purpose ofdecreasing the sound of the air flow.

[0009] In said vacuum cleaner, the air flows coming from both the mainand bypass nozzles enter the turbine housing.

[0010] The turbine and the rotary brush are always active, since thesteps of opening and closing the bypass nozzle have only the aim ofadjusting the air flow directed on the turbine.

[0011] Therefore, said vacuum cleaner always operates as a turbo-brushhead and never can operate only as a suction head.

[0012] As far as the inventors are aware, hitherto a commercial devicewhich is capable of operating both as a turbo-brush head and as a simplesuction head has not yet been developed.

[0013] The object of the present invention is to provide a device whichis capable of performing both the functions and which is easy andinexpensive to manufacture.

[0014] Said object is achieved by a device for removing dust and rubbishfrom a surface, comprising a casing provided with a suction opening, arotating brush, a turbine operationally connected to said brush, asuction nozzle having a predefined flow cross-section, and a suctionpipe connected to a suction device, said rotating brush having a shaftrotatably supported in a first housing of said casing, said turbinehaving a shaft rotatably supported in a second housing of said casing,said suction nozzle being located between said rotating brush and saidturbine for sucking an air flow from said suction opening, direct itonto said rotating brush and then towards said turbine, characterized inthat said device also includes at least a bypass duct and first valvemeans, said at least a bypass duct having a predefined flowcross-section and being designed for bypassing said second housing andsaid turbine, and connecting said suction opening and said first housingwith said suction pipe and said suction device, said first valve meansbeing able to engage with said suction nozzle and with said at least abypass duct for closing said suction nozzle and opening said at least abypass duct.

[0015] The person skilled in the art will easily understand that, in thedevice according to the invention, opening of said bypass, together withthe simultaneous closing of said suction nozzle, deactivates saidturbine and said rotating brush and causes said device to operate as asuction head only. In turn, opening of said suction nozzle, togetherwith simultaneous closing of said bypass, activates said turbine andsaid rotating brush and causes said device to operate as a turbo-brushhead.

[0016] Preferably, said first valve means are able to vary graduallysaid flow cross-section of said suction nozzle.

[0017] Advantageously, said first valve means are able to vary graduallysaid flow cross-section of said at least a bypass duct.

[0018] In particular, said first valve means are able to close graduallysaid flow cross-section of said suction nozzle, while they graduallyopen said flow cross-section of said at least a bypass duct.

[0019] Advantageously, said first valve means are connected to a manualactuating element.

[0020] Preferably, said first valve means consist of a first slide valvehaving a first sliding shutter provided with a first opening able to besuperimposed on said flow cross-section of said suction nozzle.

[0021] In an embodiment, said first sliding shutter is further providedwith a second opening able to be superimposed on said flow cross-sectionof said at least a bypass duct.

[0022] Preferably, said first and second opening of said first slidingshutter have a width greater than the width of said flow cross-sectionof said suction nozzle and, respectively, of said flow cross-section ofsaid at least a bypass duct.

[0023] Advantageously, said device also includes an auxiliary openingwhich connects said first housing to the external environment and secondvalve means able to engage with said auxiliary opening for opening itwhen said turbine undergoes a drop in power owing to obstruction of saidsuction opening, for example by a moquette or a carpet.

[0024] Preferably, said second valve means consist of a second slidevalve having a second sliding shutter provided with a third openingdesigned to be superimposed on said auxiliary opening.

[0025] Advantageously, said first and second sliding shutter areoperationally connected to a slider.

[0026] Typically, said shaft of said rotating brush is also movablysupported in said first housing and is operationally connected toactuating means capable of raising it and keeping it raised so as tomove said rotating brush away from said surface to be cleaned.

[0027] Preferably, said actuating means include two levers whichrotatably support said shaft of said rotating brush, said two leversbeing pivotably mounted in said first housing.

[0028] Advantageously, said actuating means also include a projectingelement integral with said levers, said first sliding shutter beingprovided with a ramp and a surface which engage with said projectingelement, raising it and causing it to rotate integrally with said leversfor raising said rotating brush and keeping it raised.

[0029] Preferably, said first opening of said first sliding shutter isable to be superimposed on the said flow cross-section of said suctionnozzle and/or on said flow cross-section of said at least a bypass duct.

[0030] Typically, said first opening of said first shutter has a widthgreater than the width of said flow cross-section of said suction nozzleand substantially equal to the width of said flow cross-section of saidat least a bypass duct.

[0031] In an embodiment, said bypass duct is placed under said secondhousing.

[0032] In another embodiment, a first and a second bypass duct areplaced at the sides of said second housing.

[0033] Preferably, said first sliding shutter is provided with a lateralportion able to be superimposed on said flow cross-section of saidsecond bypass duct, while said first opening is able to be superimposedon said flow cross-section of said suction nozzle and/or on said flowcross-section of said first bypass duct.

[0034] As already said, the device according to the invention offers theadvantage that it may be used both as a turbo-brush head for cleaning amoquette, a carpet and the like, and as a simple suction head forcleaning a bare surface.

[0035] In order to vary the operating mode of the device from aturbo-brush head to a simple suction head, it is simply required toactuate manually the first valve means so that they close the nozzlewhich conveys the sucked-in air flow towards the turbine and, at thesame time, open the turbine bypass duct. As a result, the turbine isdeactivated and ceases to actuate the rotating brush, while the airwhich enters via the suction opening flows directly into the suctionpipe connected to the suction device. When the operating mode as asimple suction head is selected, it is also possible to raise therotating brush from the surface to be cleaned so that it does not hinderin any way suction of the dust and rubbish.

[0036] In addition, when the operating mode as a turbo-brush head isselected and the rotating brush encounters a strong resistance and tendsto stop rotating, it is possible to activate an auxiliary opening whichallows the entry of an additional air flow directed towards the turbinewhich thus starts to rotate again and reactivates the rotating brush.

[0037] The device is particularly efficient because the exclusion of theturbine from the path of the air which flows from the suction opening tothe suction device does not produce that dispersion of energy whichoccurs when the sucked air flow interacts with the turbine.

[0038] Further characteristic features and advantages of the inventionwill now be described with reference to embodiments illustrated by wayof a non-limiting example in the accompanying figures in which:

[0039]FIG. 1 is a longitudinally sectioned partial view of a device forremoving dust and rubbish provided in accordance with the invention;

[0040]FIGS. 2 and 3 show the device of FIG. 1 in two different operatingconditions;

[0041]FIG. 4 shows a cross-sectional view along the plane IV-IV of FIG.1;

[0042]FIG. 5 shows a partial plan view of the device of FIG. 1;

[0043]FIG. 6 shows a longitudinally sectioned partial view of anotheroperating condition of the device of FIG. 1;

[0044]FIG. 7 shows a partial view sectioned along the plane VII-VII ofFIG. 6;

[0045]FIG. 8 shows a partial view sectioned along the plane VIII-VIII ofFIG. 6;

[0046]FIG. 9 shows a top view of a variant of the device for removingdust and rubbish of FIG. 1, wherein an upper part of a casing has beenremoved;

[0047]FIG. 10 shows a cross-sectional view along the plane X-X of FIG.9.

[0048]FIG. 1 shows a device 1 having a casing 2 provided with wheels 21and 20. The device 1 includes a rotating brush 8 provided with bristles9. The rotating brush 8 has a shaft 40 rotatably supported in a housing7 of the casing 2. The brush 8 is rotated, in an anti-clockwisedirection, by a turbine 11 via a toothed belt 17 and toothed pulleys,not shown. The turbine 11 has a shaft 41 and a rotor 42 provided withradial vanes 43. The shaft 41 of the turbine 11 is rotatably supportedin a housing 12 in the casing 2. A suction pipe 14, which is fixed to aunion 13 of the casing 2, is connected to a suction device not shown, inthat it is known to the person skilled in the art. The union 13 alsocommunicates with the housing 12 of the turbine 11 via an opening 19.

[0049] The casing 2 is provided with a suction opening 5 inside whichthe rotating brush 8 is arranged and has a sliding base 3 which makescontact with a surface to be cleaned 4. A suction nozzle 15 having apredefined flow cross-section, is located between the housing 7 of therotating brush 8 and the housing 12 of the turbine 11. The nozzle 15 hasan inlet port 6 communicating with the housing 7 of the rotating brush 8and an outlet port 44 which emerges in the vicinity of the bottom vanes43 of the turbine 11.

[0050] A duct 45 for bypassing the housing 12 of the turbine 11 isplaced in the lower zone of the casing 2, under the housing 12. Thebypass duct 45 has a predefined flow cross-section and has an inlet port46 communicating with the housing 7 of the rotating brush 8 and anoutlet port 47 communicating with the union 13 and the suction pipe 14.Thus, the bypass duct 45 directly connects the housing 7 of the rotatingbrush 8 with the union 13 and the suction pipe 14.

[0051] A slide valve 22 has a plate-like shutter 48 which engages withthe suction nozzle 15 and the bypass duct 45. The shutter 48 is mountedinside a guide channel 49 and is slidable in a transverse direction. Thesliding shutter 48 has two openings 18 and 23 (FIGS. 2 and 4). Theopening 18 is designed to be superimposed on the inlet port 6 of thesuction nozzle 15 and to connect the housing 7 of the brush 8 to thenozzle 15. The opening 23 is designed to be superimposed on the inletport 46 of the bypass duct 45 and to connect the housing 7 of the brush8 to the bypass duct 45. The sliding shutter 48 is provided with atongue 50 which emerges from a transverse slot 51 in the casing 2 and isfixed to a slider 52 which can be actuated manually by the person usingthe device 1.

[0052] The slider 52 is integral with a slide valve 55 provided with asliding shutter 53 which engages with an auxiliary opening 31 in thecasing 2. The shutter 53 has an opening 54 (FIGS. 3 and 5) which isdesigned to be superimposed on the auxiliary opening 31 and connect thehousing 7 of the rotating brush 8 to the external environment.

[0053] As shown in FIGS. 6, 7 and 8, the shaft 40 of the rotating brush8 is provided with two end pins 24 and bushes 25 (only one of which isshown in FIG. 7) by means of which it is rotatably supported on theouter ends of two levers 26. The levers 26 are pivotably mounted, attheir inner ends, in seats 28 in the housing 7 by means of a rod 33which renders them integral. The rod 33 is provided with a projectingelement 34, for example a cam, with which a ramp 35 and a surface 36 ofthe sliding shutter 48 of the slide valve 22 engage, as will beillustrated further below.

[0054]FIG. 1 shows the configuration of the device 1 when it is used asa turbo-brush head for cleaning fabric surfaces, such as moquettes,carpets and the like. In this condition, an operator using the device 1actuates the slider 52 (arrow A in FIG. 4) and adjusts the slidingshutter 48 of the slide valve 22 in a position where its opening 18 issuperimposed on the inlet port 6 of the suction nozzle 15 and thesuction nozzle 15 is completely open. In this position, the shutter 48closes the inlet port 46 of the bypass duct 45.

[0055] When the suction device is switched on, an air flow passesthrough the opening 5, the housing 7, the suction nozzle 15, the housing12 of the turbine 11, the union 13 and the suction pipe 14. The air flowdischarged from the suction nozzle 15 strikes the vanes 43 of theturbine 11 and causes the latter to rotate. The turbine 11, in turn,causes rotation of the brush 8 via the belt 17. Then the air flowemerges from the housing 12, through the opening 19, and, via the union13 and the pipe 14, reaches the suction device. The air flow removes thedust and the rubbish raised by the action of the bristles 9 of therotating brush 8 passing over the surface to be cleaned.

[0056] The bristles 9 of the rotating brush 8 project from the suctionopening 5 and, with their rotary movement, raise the dust and rubbishpresent on the surface to be cleaned, facilitating suction thereof.

[0057] A further advantage of the present invention is that, when theoperator wishes to cause operation of the rotating brush 8 at a speed ofrotation lower than the maximum speed, for example in order to cleanvaluable or delicate fabrics, he/she actuates the shutter 48 of theslide valve 22 by means of the slider 52 and displaces it in a positionwhere the opening 18 is partly superimposed on the inlet port 6 of thesuction nozzle 15 and the opening 23 is partly superimposed on the inletport 46 of the bypass duct 45, depending on the desired reduction inspeed. In this way, the flow cross-section of the nozzle 15 is reducedand the air flow which strikes the turbine 11 is proportionally reduced.The remaining part of the air flow, instead, is conveyed to the suctiondevice via the bypass duct 45. Thus, the turbine 11 operates at a speedof rotation less than the maximum speed and the brush 8 rotates at apredefined lower speed.

[0058] In this operating condition, the reduction in the speed ofrotation of the turbine is achieved without reducing the flowrate of theair which sucks the dust and rubbish from the surface to be cleaned.

[0059]FIG. 2 shows the configuration of the device 1 when it operatesonly as a suction head. In this case, the operator using the device 1actuates the slider 52 and adjusts the sliding shutter 48 of the slidevalve 22 in a position where the opening 18 is displaced from the inletport 6 of the suction nozzle 15 and the opening 23 is superimposed onthe inlet port 46 of the bypass duct 45. Thus, the suction nozzle 15 isclosed and the turbine 11 and the rotating brush 8 are deactivated,while the bypass duct 45 is completely open. The air flow which removesthe dust and rubbish from the surface to be cleaned is sucked via theopening 5, pass through the housing 7 and is directly conveyed by meansof the bypass duct 45 to the union 13 and the suction pipe 14.

[0060] The rotating brush 8 is moved away from the surface 4, as will beillustrated further below.

[0061]FIG. 3 shows the configuration of the device 1 when, duringcleaning of surfaces 4 lined with fabric, the rotating brush 8 tends tostop rotating because the fabric to be cleaned is sucked up against thesuction opening 5 and obstructs it.

[0062] In this case, the operator, by means of the slider 52, displacesthe shutter 53 and causes the opening 54 to superimpose on the auxiliaryopening 31 connecting the housing 7 to the external environment.Concurrently, the sliding shutter 48 keeps the inlet port 6 of thesuction nozzle 15 open. Via the opening 31 and the suction nozzle 15, asecondary air flow is produced which reaches the turbine 11 and causesit to start operating again.

[0063] FIGS. 6 to 8 show the configuration of the device 1 when therotating brush 8 is raised.

[0064] When the device 1 operates as a suction head only, the slidingshutter 48 is actuated so as to intercept the suction nozzle 15 andleave the bypass 45 open (FIG. 8). While the shutter 48 slides towardsthe left in the FIG. 8, its ramp 35 comes into contact with theprojecting element 34 and raises it, causing it to rotate integrallywith the rod 33. The projecting element 34 and the rod 33, in turn,rotate the levers 26 which raise the rotating brush 8 and cause it tomove away from the suction opening 5. When the projecting element 34reaches the surface 36, the levers 26 are locked and keep the rotatingbrush 8 in the completely raised position.

[0065] Therefore, changing the position of the shutter 48 of the slidevalve 22 simultaneously causes a change in the direction of the air flowsucked in by the suction device via the pipe 14 and heightwiseadjustment of the rotating brush 8.

[0066] In order to modify the bearing pressure exerted by the rotatingbrush 8 on the surface to be cleaned, said pressure being determined bythe tractional force of the drive belt 17, loading or lightening deviceswhich exert their action on the levers 26 may be used.

[0067]FIGS. 9 and 10 show a device 100 for removing dust and rubbishwhere the parts as those of the device 1 are denoted by the samereference numerals.

[0068] The device 100 has a casing 102 including the housing 7 of therotating brush 8 and the housing 12 of turbine 11. It further includestwo ducts 145 and 245 which bypass the housing 12 of the turbine 11 andare placed at the sides of the housing 12 of turbine 11. Both the bypassducts 145 and 245 directly connect the housing 7 of the rotating brush 8with a joint 113 and the suction pipe 14. The bypass ducts 145 and 245have respective inlet ports 146 and 246 (FIG. 10) and respective outletports 147 and 247.

[0069] A slide valve 122 has a plate-like sliding shutter 148 engageablewith the suction nozzle 15 and bypass ducts 145 and 245. The shutter 148slides in a transverse direction (arrow A) and is connected to theslider 52 which is actuated manually by a person using the device 100.Optionally, the slider 52 may be actuated by a conventional motor.

[0070] The sliding shutter 148 has lateral portions 110 and 111 and anintermediate opening 118. The opening 118 is designed to be superimposedon the inlet port 6 of the suction nozzle 15 when the operator wantsconnect the housing 7 of the brush 8 to the suction nozzle 15. Thelateral portion 111 of sliding shutter 148 is designed to besuperimposed to the inlet ports 246 of the bypass duct 245 and to beremoved from it for disconnecting and, respectively, connecting thehousing 7 to the bypass duct 245. The lateral portion 110 is designed tobe superimposed to the inlet ports 146 of the bypass duct 145 fordisconnecting the housing 7 from the bypass duct 145. The opening 118 isalso designed to be superimposed on the inlet port 146 of the bypassduct 145 for connecting the housing 7 of the brush 8 to the bypass duct145. Preferably, the opening 118 is wider than the cross-section of theinlet port 6 and substantially equal to the width of the cross-sectionof the inlet port 146.

[0071] The device 100 operates as the device 1.

[0072] When the operator wants operate the device 100 as a turbo-brushhead, he has to adjust the sliding shutter 148 of the slide valve 122 ina position where the opening 118 is superimposed on the inlet port 6 ofthe suction nozzle 15. In this position of the shutter 148, the suctionnozzle 15 is completely open, while the inlet ports 146 and 246 of thebypass ducts 145 and 245 are closed by the lateral portions 110 and 111,respectively (FIG. 10).

[0073] The turbine 11 is active and drives the brush 8.

[0074] When the operator wants operate the device 100 as a suction headonly, he has to displace the sliding shutter 148 of the slide valve 122to the left-hand side of arrow A in FIG. 10 till the shutter 148 opensthe inlet ports 146 and 246 of the bypass ducts 145 and 245,respectively, and closes the inlet port 6 of the suction nozzle 15. Inthis position of the shutter 148, the inlet port 246 is open thanks tothe displacement of the lateral portion 111 on the left, while the inletport 146 is open thanks to the concurrent displacement of the opening118 on the inlet port 146.

[0075] The turbine 11 and the rotating brush 8 are thus deactivated andthe air flow which removes the dust and rubbish from the surface to becleaned is sucked via the opening 5, passes through the housing 7 and isdirectly conveyed by means of the bypass ducts 145 and 245 to the joint113 and the suction pipe 14.

[0076] The displacement of the sliding shutter 148 in any intermediatepositions allows to vary at will the flow cross-section of the inletports 6, 146 and 246 of the suction nozzle 15 and of the bypass ducts145 and 245, respectively. It is thus possible to control the air flowswhich impact and/or bypass the turbine 11 and the housing 12.

[0077] The arrangement of the bypass ducts 145 and 245 at the sides ofthe housing 12 of the turbine 11 is preferred because it minimizes theheight of the device 100 in comparison with that of the device 1.

1. Device for removing dust and rubbish from a surface, comprising acasing provided with a suction opening, a rotating brush, a turbineoperationally connected to said brush, a suction nozzle having apredefined flow cross-section, and a suction pipe connected to a suctiondevice, said rotating brush having a shaft rotatably supported in afirst housing of said casing, said turbine having a shaft rotatablysupported in a second housing of said casing, said suction nozzle beinglocated between said rotating brush and said turbine for sucking an airflow from said suction opening, direct it onto said rotating brush andthen towards said turbine, characterized in that said device alsoincludes at least a bypass duct and first valve means, said at least abypass duct having a predefined flow cross-section and being designedfor bypassing said second housing and said turbine, and connecting saidsuction opening and said first housing with said suction pipe and saidsuction device, said first valve means being able to engage with saidsuction nozzle and with said at least a bypass duct for closing saidsuction nozzle and opening said at least a bypass duct.
 2. Deviceaccording to claim 1 , characterized in that said first valve means areable to vary gradually said flow cross-section of said suction nozzle.3. Device according to claim 1 , characterized in that said first valvemeans are able to vary gradually said flow cross-section of said atleast a bypass duct.
 4. Device according to claim 1 , characterized inthat said first valve means are able to close gradually said flowcross-section of said suction nozzle, while they gradually open saidflow cross-section of said at least a bypass duct.
 5. Device accordingto claim 1 , characterized in that said first valve means are connectedto a manual actuating element.
 6. Device according to claim 1 ,characterized in that said first valve means consist of a first slidevalve having a first sliding shutter provided with a first opening ableto be superimposed on said flow cross-section of said suction nozzle. 7.Device according to claim 6 , characterized in that said first slidingshutter is further provided with a second opening able to besuperimposed on said flow cross-section of said at least a bypass duct.8. Device according to claims 6 and 7, characterized in that said firstand second opening of said first sliding shutter have a width greaterthan the width of said flow cross-section of said suction nozzle and,respectively, of said flow cross-section of said at least a bypass duct.9. Device according to claim 1 , characterized in that it also includesan auxiliary opening which connects said first housing to the externalenvironment and second valve means able to engage with said auxiliaryopening for opening it when said turbine undergoes a drop in power owingto obstruction of said suction opening.
 10. Device according to claim 9, characterized in that said second valve means consist of a secondslide valve having a second sliding shutter provided with a thirdopening designed to be superimposed on said auxiliary opening. 11.Device according to claims 6 and 10, characterized in that said firstand second sliding shutter are operationally connected to a slider. 12.Device according to claim 1 , characterized in that said shaft of saidrotating brush is also movably supported in said first housing and isoperationally connected to actuating means capable of raising it andkeeping it raised so as to move said rotating brush away from saidsurface to be cleaned.
 13. Device according to claim 12 , characterizedin that said actuating means include two levers which rotatably supportsaid shaft of said rotating brush, said two levers being pivotablymounted in said first housing.
 14. Device according to claims 6 and 13,characterized in that said actuating means also include a projectingelement integral with said levers, said first sliding shutter beingprovided with a ramp and a surface which engage with said projectingelement, raising it and causing it to rotate integrally with said leversfor raising said rotating brush and keeping it raised.
 15. Deviceaccording to claim 6 , characterized in that said first opening of saidfirst sliding shutter is able to be superimposed on the said flowcross-section of said suction nozzle and/or on said flow cross-sectionof said at least a bypass duct.
 16. Device according to claim 15characterized in that said first opening of said first shutter has awidth greater than the width of said flow cross-section of said suctionnozzle and substantially equal to the width of said flow cross-sectionof said at least a bypass duct.
 17. Device according to claim 1 ,characterized in that said bypass duct is placed under said secondhousing.
 18. Device according to claim 1 , characterized in that a firstand a second bypass duct are placed at the sides of said second housing.19. Device according to claims 15 and 18, characterized in that saidfirst sliding shutter is provided with a lateral portion able to besuperimposed on said flow cross-section of said second bypass duct,while said first opening is able to be superimposed on said flowcross-section of said suction nozzle and/or on said flow cross-sectionof said first bypass duct.